With the current increase in greenhouse gas emission reduction obligations through conventions on climate change, carbon dioxide markets have become activated, and thus new renewable energy is receiving attention.
Examples of new renewable energy may include solar light, wind power, biomass, geothermal power, water power, tidal power, etc. In particular, a solar cell is a system for producing electricity using solar light, which is an infinite clean energy source, the rapid growth of which is expected, and such a solar cell functions to directly convert light into electricity.
Also, solar cells are the only power source that decreases power generation costs, and adopt the energy that obviates the construction of power plants, incurs only maintenance costs, and is safe and environmentally friendly, unlike nuclear energy.
A variety of kinds of solar cells are provided, which include typical crystalline solar cells, CIGS as thin-film-type solar cells, and DSSC as next-generation solar cells.
A silicon thin-film solar cell includes an amorphous silicon (a-Si:H) solar cell, which was first developed and distributed, and a microcrystalline silicon (μc-Si:H) solar cell for increasing light absorption efficiency. Furthermore, the silicon thin-film solar cell may be exemplified by a silicon thin-film solar cell having a tandem structure (a-Si:H/c-Si:H) resulting from layering two solar cells having different band gaps.
In particular, a crystalline solar cell is advantageous in terms of high efficiency. In order to further increase the efficiency of the crystalline solar cell, the surface thereof is textured in a manner in which the flat surface of a silicon wafer is roughened through dry etching or wet etching to thus reduce the reflectance thereof.
Korean Patent Application Publication No. 2013-0043051 discloses an etchant composition for texturing a crystalline silicon wafer and an etching process for texturing, especially an etchant composition for texturing a crystalline silicon wafer and an etching process for texturing in which a specific pyramid structure is formed so as to reduce reflectance. Although this patent may reduce reflectance, the reduction is not significant.
Thus, a silicon wafer and a solar cell using the same are required, in which reflectance may be significantly decreased when the silicon wafer is utilized in the solar cell, and the carrier lifetime may be improved.